The present invention relates to a bicycle engine and more particularly to a bicycle engine having a transmission roller at the end of the engine driving shaft which is contacted with or moved away from the bicycle tire by selectively inclining the engine.
The bicycle engine in accordance with applicant's prior U.S. Pat. No. 4,014,402 has no special starting device for the engine itself. Therefore, the engine is started by inclining the engine frame by means of a lever, thereby causing the transmission roller provided at the end of the driving shaft to contact the tire and by pedaling the bicycle to rotate the wheels. Thus, the rotation of the wheels is transmitted to the engine via the transmission roller. When one wants to stop temporarily for example at an intersection, it is necessary to operate the lever to turn the engine frame upward and move the transmission roller away from the tire in order to cut off the transmission of engine rotation to the wheel.
Such an operation is about the same as operating a clutch, but in the case of this prior engine, the engine itself had to be inclined to acheive the same effect as the clutch. Operating the lever was more burdensome compared to an ordinary clutch. It is, therefore, desirable for safety purposes to eliminate this motion of inclining the engine once the engine is started. This can be achieved simply by providing a clutch on the driving shaft, except that an ordinary clutch requires a separate lever to connect or disconnect the clutch and further complicates the operation of the bicycle. A centrifugal clutch which utilizes the engine rotation is a conceivable solution, and yet such a clutch may be useful for stopping the bicycle temporarily while keeping the engine "on", but cannot transmit the wheel rotation to the engine as the operator steps on the pedals. Thus, this type of clutch requires a separate engine starting device and complicates the whole mechanism.
In view of such difficulties, the object of this invention is to provide a clutch mechanism which can start the engine by transmitting the wheel rotation started as the operator steps on the pedals since the transmission roller is kept in contact with the wheel tire, and which also can prevent transmission of the engine rotation to the transmission roller once the engine has been started and it is being kept in its idle condition.